Indelible prep-resistant gentian violet ink provides an effective means for skin marking with a built-in measuring ruler on the marker in centimeters and inches. The skin-friendly ink doesn't contain heavy metals or Latex making it completely non-toxic, non-tattooing, non-irritating, or non-smearing. A non-rolling ergonomic design makes for easy and accurate marking. Additionally, the markers are incinerable and available sterile and non-sterile in custom trays and packs.